Edexcel A-level Biology
Free Edexcel A-level Biology revision for Edexcel Biology (9BI0): 16 topics and 418 short lessons, each with R.E.C.I.P.E. recall steps and a quiz. The topics follow the Edexcel specification.
1. Cellular Respiration
- Cellular Respiration
- ATP
- Aerobic Respiration
- Respiration in the Cytoplasm
- Mitochondria
- Hydrogen Acceptors
- Investigating the Rate of Respiration
- Investigating the Site of ATP Synthesis
- Glycolysis
- Anaerobic Respiration in Mammals
- Lactate
- Sprint Athletes
- Anaerobic Respiration in Plants and Fungi
- Discovery of Glycolysis
- Aerobic Respiration: Summary
- The Link Reaction
- The Krebs Cycle
- The Electron Transport Chain
- Chemiosmosis
- Net Gain of ATP
2. Photosynthesis
- Autotrophs and Heterotrophs
- The Process of Photosynthesis
- Chloroplasts
- Chlorophyll
- Absorption Spectrum Chlorophyll
- Chromatography
- Photosystems
- The Light-Dependent Reactions
- Cyclic Photophosphorylation
- Non-Cyclic Photophosphorylation
- The Light-Independent Stage
- The Calvin Cycle
- The Products of Photosynthesis
- C4 Plants
- Rubisco
- Limiting Factors of Photosynthesis
- Light
- Carbon Dioxide
- Temperature
- Limiting Factors in the Wild
3. Bacteria and Disease
- Culturing Microorganisms
- Aseptic Culture Techniques
- Selective Media
- Growing a Pure Culture
- Counting the Number of Cells
- Turbidity
- Dilution Plating
- Area and Mass of Fungi
- Growth of Bacterial Colonies
- Logarithmic Scale
- Exponential Growth
- Bacterial Toxins
- Endotoxins
- Salmonella spp.
- Exotoxins
- Staphylococcus spp.
- Host Tissue Invasion
- Mycobacterium tuberculosis
- Antibiotics
- Broad-spectrum, Narrow spectrum, Bacteriostatic and Bactericidal
- Antimetabolites
- Protein synthesis Inhibitors
- Cell Wall Agents
- Cell Membrane Agents
- DNA Gyrase Inhibitors
- Antibiotic Resistance
- Creating Drug-Resistant Bacteria
- MRSA
- Clostridium difficile
- Prevention and Control of Infection
4. Viruses, Fungi and Protozoa
- Viral Diseases
- Influenza
- Transmission of Influenza
- Pathogenic Effects of Influenza
- Treatment and Control of Influenza
- Fungi as Pathogens
- Puccinia graminis
- Transmission of Stem Rust
- Pathogenic Effects of Stem Rust
- Treatment and Control of Stem Rust
- Protozoa as Pathogens
- Plasmodium spp.
- Transmission of Malaria
- Pathogenic Effects of Malaria
- Endemic Diseases
- Treatment, Prevention and Control of Malaria
- Preventing the Breeding of Mosquitoes
5. Response to Infection
- Cell Recognition
- Non-specific Responses
- Fevers
- Phagocytosis
- Lymphocytes
- B cells
- T Cells
- The Humoral Response
- The Effector Stage
- Clonal Selection
- Antibodies
- The Cell-Mediated Response
- Cytotoxic T Cells
- Primary and Secondary Immune Response
- Types of Immunity
- Artificial Passive Immunity
- Artificial Active Immunity - Vaccines
- Herd Immunity
- Eradicating Disease
- The Pros and Cons of Vaccination
6. Gene Sequencing
7. Gene Expression
- Gene Expression
- Gene Probes
- Control of Gene Expression
- Transcription Factors
- RNA Splicing
- Epigenetics
- DNA Methylation
- DNA Demethylation
- Euchromatin and Heterochromatin
- Histone Acetylation
- Histone Methylation
- non-Coding RNA
- siRNA
- Cell Differentiation
- Early Stages of Development
- Stem Cells
- Embryonic Stem Cells
- Umbilical Cord Stem Cells
- Adult Stem Cells
- Determination of Cell Type
- Evidence for Cell Determination
- Development of an Organism
- Epigenetic Control of Development
- Epigenetic Control of Gene Expression
- Stem Cell Therapy
- Therapeutic Cloning
- Gene Editing
- Potential Benefits of Stem Cell Therapy
- Pitfalls of Stem Cell Therapy
- Induced Pluripotent Stem Cells
- Diseases that Could Be Treated
- Type I Diabetes
- Damaged Nerves
- Organs for Transplants
- Stem Cell Success
- Ethical Questions
- Using Embryonic Stem Cells
- Advantages of Therapeutic Cloning
- Advantages of iPS Cells
8. Gene Technology
- Producing Recombinant DNA
- Identifying Transformed Organisms
- Vectors
- Gene Guns
- Liposome Wrapping
- Microinjection
- Gene Silencing
- Transgenic Plants
- Cloning Plants
- Genetic Modification of Crops
- Genetic Modification of Soya Bean
- Gene Technology in Animals
- Gene Technology in Humans
- Knockout Mice
- Human Gene Therapy
- Ethics
- Safety of GM Crops
9. Genetic Information
- Meiosis and Genetic Variation
- Mutation and Genetic Variation
- Different Types of Mutation
- Random Fertilisation
- Genetics and Inheritance
- Alleles
- Polygenic Traits
- Monohybrid Crosses
- Test Cross
- Sampling Errors
- Mendel
- Law of Segregation
- Law of Independent Assortment
- Multiple Alleles
- Codominance
- Dihybrid Crosses
- Drosophila
- Probability
- Chi-Squared Test
- Chi-Squared Test - Monohybrid Crosses
- Chi-Squared Test- Dihybrid Crosses
- Gene Linkage
- Identifying Linked Genes
- Chromosome Mapping
- Sex-Linkage
- Pedigree Diagrams
- The Albino Trait
- Sex-Linked Diseases
- Red-Green Colour Blindness
- Haemophilia
10. Gene Pools
- Population Genetics
- Allele Frequency
- Hardy Weinberg Equilibrium
- Hardy Weinberg Equation
- Conditions of the Hardy Weinberg Equilibrium
- Mutations
- Non-Random Mating
- Different Sized Populations
- Isolation
- Selection Pressure
- Population Bottlenecks
- The Founder Effect
- Stabilising Selection
- Directional Selection
- Disruptive Selection
- Genetic Drift
11. Chemical Control
- Homeostasis
- Feedback Systems
- Negative Feedback
- Positive Feedback
- Chemical Control
- Endocrine Glands
- Hormone Release System
- Pituitary Gland
- Second Messenger System
- Plant Stimuli
- Plant Responses
- Plant Growth
- Auxins
- How Auxins Work
- Gibberellins
- Cytokinins
- Synergy and Antagonism
- Apical Dominance
- Sensory Systems in Plants
- Phytochromes
- Photoperiodism
- Long Day Plants
- Short Day Plants
- Day Neutral Plants
- Signal Detection
- Discovery
- Photomorphogenesis
- Germination and Photomorphogenesis
- Phytochromes, Photomorphogenesis and Tropisms
- Phytochrome as a Transcription Factor
12. Mammalian Nervous System
- Nervous System
- Structure and Function of Neurones
- Nerve Impulses
- Myelinated Neurones
- Speed of Nerve Impulses
- Investigating Nerve Impulses
- Resting Potential
- Action Potential
- Depolarisation
- Repolarisation
- Hyperpolarisation
- Refractory Period
- Transmission of Nerve Impulses
- Saltatory Conduction
- Synapses
- Pre-synaptic Membrane
- Post-Synaptic Membrane
- Neurotransmitters
- Drugs
- Nicotine
- Lidocaine
- Cobra Venom
- Sensory Receptors
- The Human Eye
- The Retina
- Rods
- Cones
- Colour Vision
- Formation of the Brain
- Major Areas of the Brain
- Other Areas of the Brain
- Spinal Cord
- Reflex Responses
- Peripheral Nervous System
- Voluntary Nervous System
- Autonomic Nervous System
- Sympathetic Nervous System
- Parasympathetic Nervous System
13. Homeostasis
- Controlling the Heart Rate
- Nervous Control of the Heart
- Baroreceptors
- Chemoreceptors
- Hormonal Control of the Heart
- Additional Responses
- Protein Homeostasis in the Liver
- Osmoregulation
- Osmoregulation in Mammals
- Structure and Function of the Kidney
- Ultrafiltration
- Selective Reabsorption
- Proximal Convoluted Tubule
- Loop of Henle
- Countercurrent Multiplier
- Distal Convoluted Tubule
- Collecting Duct
- Urine
- Adaptations
- Control of Osmoregulation
- ADH
- Negative Feedback Control
- Extra Feedback
- Diabetes Insipidus
- Thermoregulation
- Losing or Gaining Heat
- Control of Body Temperature
- Endotherms
- Ectotherms
- Thermoregulation in Endotherms
- The Skin
- Keeping Cool
- Keeping Warm
- Control of Core Body Temperature
- Vasodilation
- Vasoconstriction
- Adaptations for Cold Environments
- Adaptations for Hot Environments
- Cooling The Brain
- Behavioural Control of Body Temperature
- Cape Ground Squirrel
14. The Nature of Ecosystems
- Ecosystem
- Habitat
- Community
- Abiotic Factors
- Biotic Factors
- Biosphere
- Primary Succession
- Climax Community
- Secondary Succession
- Case Study: Sand Dune Succession
- Light
- Temperature
- Wind and Water Currents
- Water Availability
- Oxygen Availability
- Edaphic Factors
- Predation
- Finding a Mate
- Territory
- Parasitism and Disease
- Case Study: Snowshoe Hare and Lynx
- Case Study: Red Grouse and Parasites
- Density Dependent Factors
- Density Independent Factors
- Competition
- Intraspecific Competition
- Interspecific Competition
- Species Abundance
- Species Distribution
- Ecological Techniques
- Quadrats
- ACFOR Scale
- Point Quadrats
- Permanent Quadrats
- Transects
- More Ecological Techniques
- Hypothesis Testing
- Spearman's Rank Correlation Coefficient
- Student's t-Test
15. The Efficiency of Ecosystems
- Food Chains
- Food Webs
- Ecological Pyramids
- Pyramid of Numbers
- Pyramid of Biomass
- Inverted Pyramids of Numbers
- Energy Losses in Producers
- Energy Losses between Consumers
- Efficiency of Energy Transfer
- Gross Primary Productivity
- Net Primary Productivity
- The Limitations of Efficiency Calculations
- Energy Transfer and Food Chain Length
- Nutrient Recycling
- Conditions for Recycling Nutrients
- Microorganisms in the Nitrogen Cycle
- Microorganisms in the Carbon Cycle
- Short-term Carbon Sinks
- Long-term Carbon Sinks
- Human Influence
16. Human Influence on Ecosystems
- Human Population Explosion
- Climate Change
- Depletion of Biological Resources
- Loss of Biodiversity
- The Burden of Proof
- Evaluating Studies
- Greenhouse Effect
- Evidence for the Global Temperature Increase
- Analysis of Ice Cores
- Data Reliability
- Methane
- Correlation or Causation
- Models of Global Warming
- Effects of Climate Change
- Risk of Flooding
- The Effect on Organisms
- Changes in Species Distribution
- Farming: Depletion of Resources
- Fishing: Depletion of Resources
- Anthropogenic Changes in the Ocean
- Problems with Conservation
- Fish Farming and Aquaculture
- Endangered Species
- Extinction
- Human Causes of Extinction
- Conserving Biodiversity
- CITES
- CITES Successes
- Limitations of CITES